How to Create an Array in Ruby

There are three primary ways to create an array in Ruby: the array literal, building the array and returning an array. An array is most simply defined as a variable that holds a set of values. Each of the three ways to create an array in Ruby is best used in different situations, so being familiar with all of them can be quite useful.

Instructions

Create the Array Literal in Ruby

1. Choose a variable. In the examples the variable is assigned the term "array". Your variable can be assigned whatever name or symbol you prefer.

2. Create an array literal from a list of values you already know. Look at the two examples. The first example creates a list of states, the second a list of numbers:
   array = ["Maine", "Michigan", "California"]
array = [1, 2, 3]

3. Mix types in a array if you have more than one type of value. Ruby is different than a static languages like Java, in that arrays can hold more than one type. So if your values are both words and numbers the literal array can reflect that. For example:
   array = ["Maine", 7, 12.3]

4. Utilize the shortcut available for a literal array of just strings. It will save time and effort spent on typing all the quote characters. Instead, you can do this:
   array = %w{Maine Michigan California}

Build the Array in Ruby

1. Apply this method when you don't know all the values you want to assign to the array when you write the program.

2. Use the Array class constructor to make a new empty array object. Here "arr" is now an empty array object, one with no specified values:
   arr = Array.new

3. Add, or append, elements to the end of the array with the "<<" operator. Used on the end of arrays, "<<" is referred to as the append operator. Here we want to collect a number of strings from the user. Since we don't know what the user will input, we create the empty array and add variables to the end of it:
   arr = Array.new#
   Keep reading lines from the keyboard until "end" is typed:
   while l=gets.chomp and l != "end" do arr << l end

Return the Array in Ruby

1. Use the phrase "to_a" for shorthand for "to array". All classes that use the Enumerable module can be turned into arrays with "to_a". This is the most common method to return the array and has the benefit of being easy to change.

2. Assign, for example, an array with the numbers 1 to 10 to a variable. You could use the long version: a=[1,2,3,4,5,6,7,8,9,10] or use the shorthand: a=(1..10).to_a.
   With the shorthand it would be much easier to change the values from 1 to 10 to, for example, 7 to 22 as shown here:
   a=(7..22).to_a

Tips & Warnings

• In the array literal any numbers you put your array will be String objects, not Numerics, so don't try to do math with them.